Sunday, January 18, 2015

Update from the New Zealand bittern research team:
This season, as well as monitoring bitterns at key wetlands nationally, the bittern team has been busy calibrating our monitoring methods. Our aim has been to see how the number of bitterns detected with each method compares with the actual number of bitterns present at the site. To do this we’ve needed to capture as many bitterns as possible at one site (Lake Whatumā). Each captured bittern has been marked through the attachment of a radio transmitter. The attachment of these transmitters enables us to re-find and identify marked birds even when they’re hidden in the dense Raupo. Bitterns are difficult to catch due to their cautious nature and the inaccessibility of their natural habitat. A few bitterns have been caught before in New Zealand, but only by firing a net gun onto the bird from a helicopter - something that is very risky for the bird as well as expensive. To avoid having to use these intrusive methods we’ve been trialling some capture methods that have been used on closely related bittern species overseas. This is the first time in New Zealand that Australasian bitterns have been studied intensively like this. As very little is known about bitterns we are hoping that data from this study can also answer questions like: Where do bitterns go after the breeding season? What habitat types are important to bitterns for feeding and breeding? How big are home range sizes? And do bitterns come back to the same sites every year to breed? These are important questions that no one has the answers for yet. Once answered, this knowledge will be used to identify and manage sites that are important for bitterns, helping us to help prevent the extinction of this fascinating Endangered bird.
This season our work was partly funded through the Arawai Kakariki Project and a Ducks Unlimited NZ grant.